f2fs: support idmapped mounts

This patch enables idmapped mounts for f2fs, since all dedicated helpers
for this functionality existsm, so, in this patch we just pass down the
user_namespace argument from the VFS methods to the relevant helpers.

Simple idmap example on f2fs image:

1. truncate -s 128M f2fs.img
2. mkfs.f2fs f2fs.img
3. mount f2fs.img /mnt/f2fs/
4. touch /mnt/f2fs/file

5. ls -ln /mnt/f2fs/
total 0
-rw-r--r-- 1 0 0 0 2月   4 13:17 file

6. ./mount-idmapped --map-mount b:0:1001:1 /mnt/f2fs/ /mnt/scratch_f2fs/

7. ls -ln /mnt/scratch_f2fs/
total 0
-rw-r--r-- 1 1001 1001 0 2月   4 13:17 file

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f816d7d1987d..22fb4d3b1170 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4539,7 +4539,7 @@ static struct file_system_type f2fs_fs_type = {
 	.name		= "f2fs",
 	.mount		= f2fs_mount,
 	.kill_sb	= kill_f2fs_super,
-	.fs_flags	= FS_REQUIRES_DEV,
+	.fs_flags	= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
 };
 MODULE_ALIAS_FS("f2fs");